QHY8 is a relativity airproof not the full airproof . To avoid the dew appear on CCD sensor you need to do the following things.
1.QHY8's CCD has a metal board. It is a cold finger and it can prevent the dew form on CCD glass surface. If the board has oil, It will reduce the capability to absorb the water. Please clean this board.
2.Store the QHY8 into the fully airproof box with silion gel . There is a rubber plug on side of QHY8. You can take off it when store into box. And install it before taking camera out of box.
3.After finished using please store the camera into the airproof box again.
4.Don't forget to install the M42 TO M42 adapter with optic window. It will keep the CCD in relativity airproof.
If you need a full air proof CCD chamber, You need consider QHY8PRO/8L
CCD LABS Q453 dew issue
CCD LABS Q453 is a modified version of QHY8. A thick glass and some foam been added into QHY8 camera. This modification can reduce the room between ccd sensor and the optic windows.But because the thick glass is too close to ccd sensor. The surface of this glass is easy to get dew.
If you meet this issue. We suggest you change it back to standard QHY8 construction. Please following the way:
1.Open camera and take off the thick glass and the forum between this glass and CCD sensor
2.Clean the metal board of CCD sensor. Escpcially clean the oil. The metal board is called cold finger and it can prevent the dew form on CCD sensor glass. The dew will become ice get on the surface of the cold finger instead of the CCD sensor glass.
3.Close camera. Install the M42 to M42 adapter with IR glass window.
4.Following the FAQ of "How to avoid the dew on CCD sensor surface" in this page.